As is known, in a gas-turbine plant the secondary-air circuit is a fluid network that takes a part of the flow of air from the compression line and uses it for cooling the mechanical components of the turbine exposed to the action of hot gases, in particular the fixed and mobile blades.
The efficiency of the secondary-air circuit has a marked effect both on the overall efficiency of the gas turbine and also on the pollutant emissions. There is thus evident the importance of methods that enable study and analysis of the behaviour of the secondary-air network and its interactions with the other sections of the plant (compressor and turbine).
The methods of analysis currently available are not, however, satisfactory, principally because they do not enable an adequate modelling of the secondary-air circuit. In particular, it is not possible to take adequately into account characteristic loss elements and work and heat exchanges that occur with the hot parts of the turbine.